Din 16742 - Tg5 [ PC ]

| Criteria | Requirement | |--------------------------------|-------------------------------------------------------| | Typical tolerance at 50 mm | ±0.30 mm | | Draft angle for 30 mm depth | ≥ 1.0° per side | | Geometric tolerance per 100 mm | 0.25 – 0.30 mm | | Suitable materials | Most unfilled thermoplastics, some filled compounds | | Inspection condition | 23°C, 24h after molding | | Cost impact | Neutral – standard |

If you need the official DIN 16742 document, purchase it from Beuth Verlag (Germany) or your national standards body. For most practical engineering work, the above TG5 values are sufficient for drawing notes and supplier communication.

standard is a critical German guideline for determining tolerances for plastic moulded parts, and the TG5 (Tolerance Group 5)

classification represents a middle-to-high precision tier typically achievable through standard injection moulding processes for low-shrinkage materials. Context & Performance of TG5 Precision Tier

: TG5 is part of a series (ranging from TG1 to TG9) where lower numbers denote higher precision. While TG1-TG3 are reserved for ultra-precision "fine" tolerances, TG5 is widely considered a standard "fine" tolerance for most industrial thermoplastics. Achievability

: Most reputable manufacturers can achieve TG5 tolerances consistently for materials with linear shrinkage values below 1%. For higher-shrinkage materials (like PP or PE), achieving TG5 requires highly controlled processes and precise tool design. Cost-Benefit Balance din 16742 - tg5

: Applying TG5 to a drawing ensures functional reliability without the exponential cost increase associated with ultra-tight groups (TG1–TG3). It is the "sweet spot" for parts requiring fit-and-function accuracy without excessive scrap rates. Key Strengths of the Standard Simplification

: It eliminates the need for redundant "habitual tolerances" on drawings by providing a generalized table for linear and angular dimensions. Process Specificity : The standard distinguishes between mold-fixed dimensions (formed by a single mold part) and non-mold-fixed dimensions

(affected by the movement of mold components), allowing for more realistic tolerance expectations based on tool mechanics. Supply Chain Alignment : Particularly in the European and German automotive supply chains

, referencing DIN 16742 TG5 is a clear signal of engineering rigor and quality expectations. Current Status & Replacement

To determine if TG5 is appropriate for a part, engineers should conduct a tolerance analysis: If you need the official DIN 16742 document,

Before dissecting TG5, one must understand the parent standard. DIN 16742 (formerly VDI 2006) is the German industry standard for Tolerances for injection-moulded plastic parts. Unlike metal machining standards, plastic tolerancing must account for unique variables:

DIN 16742 replaces older systems and harmonizes with global standards (ISO 20457), but remains stricter and more detailed. It defines tolerance classes from TG1 (very coarse) to TG8 (extremely fine). The most commonly specified class for functional parts is TG5.

The molder must design the steel mold to compensate for shrinkage. Under TG5, the allowed deviation from nominal shrinkage is tightly managed. For example, if the material datasheet says 0.5% shrinkage, the molder cannot let real shrinkage drift between 0.4% and 0.6%—TG5 forces a narrower band (e.g., 0.47%–0.53%).

Dimensional tolerances depend on the nominal size range (mm) of the feature. Below is a simplified table for TG5 (based on DIN 16742, general tolerances for non-critical dimensions):

| Nominal dimension (mm) | Tolerance ± (mm) | |------------------------|------------------| | 0 – 3 | ±0.08 | | 3 – 6 | ±0.12 | | 6 – 10 | ±0.15 | | 10 – 18 | ±0.20 | | 18 – 30 | ±0.25 | | 30 – 50 | ±0.30 | | 50 – 80 | ±0.40 | | 80 – 120 | ±0.50 | | 120 – 180 | ±0.65 | | 180 – 250 | ±0.80 | | 250 – 315 | ±1.00 | | 315 – 400 | ±1.20 | To determine if TG5 is appropriate for a

⚠️ These are general linear tolerances. For functional features (e.g., fits with metal parts), tighter TG3 or TG4 is recommended.

Many molders hesitate to guarantee TG5 for three reasons:

TG5 represents the widest range of permissible tolerances defined in the standard tables. It is designated for applications where high precision is not critical to the function of the part, or where the material properties make tighter tolerances economically unviable.

Key characteristics include: